package apiooday01;

import java.util.Random;

public class ChatAtDemo {
    public static void main(String[] args) {
        //验证码
        String str ="0123    456789abcdefghyjklmnABCDEFGHJKLPOIUMN";
        String a="";
        Random rand = new Random();
        for (int i=0;i<4;i++){
            int num =rand.nextInt(30);
            a+=str.charAt(num);
        }
        System.out.println(a);
       // char c =str.charAt(5);

        str =str.replaceAll("\\s","");
       System.out.println(str);

    }
}
